Video tape recorder and recording method

ABSTRACT

The present invention is particularly applied to a video tape recorder for recording a video signal of an HDTV (high-definition television) on a magnetic tape. In the video tape recorder, the recording position of the head of each pack unit is set so as to have a predetermined relationship with the recording position determined by the corresponding time management information.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a video tape recorder and a method ofrecording data on a magnetic tape. Particularly, the present inventioncan be applied to a video tape recorder that records a video signal ofan HDTV (high definition television) on a magnetic tape. The entirevideo tape recorder according to the present invention can efficientlybe structured by setting the recording position of the head of each packunit so as to have a predetermined relationship with the recordingposition determined by the corresponding time management information.

2. Background Art

Heretofore, video tape recorders for recording and/or reproducing videosignals of HDTVs (hereinafter referred to as HD signals) have beensuggested in, for example, Japanese Unexamined Patent ApplicationPublication No. 2001-291335.

Japanese Unexamined Patent Application Publication No. 2001-291335discloses a video tape recorder that effectively utilizes a magnetictape to record HD signals by compiling various signals relating to theHD signals into the first areas of multiple tracks to be subjected tointerleave in units of allocation cycles of I pictures and recording thecompiled signals.

However, it would appear that various devices are further required forpractical use in a video tape recorder of this type for recording HDsignals. Specifically, it seems that the entire structure can besimplified and, furthermore, a variety of processing can be simplifiedif the recording and reproduction systems can further efficiently bestructured.

DISCLOSURE OF INVENTION

In consideration of the above problems, the present invention provides avideo tape recorder capable of being efficiently structured and arecoding method.

In order to solve the above problems, the present invention is appliedto a video tape recorder in which the delay time of delay means isvaried such that the recording position of the head of each pack unithas a predetermined relationship with the recording position determinedby the corresponding time management information.

With the structure of the video tape recorder according to the presentinvention, since the delay time of the delay means is varied such thatthe recording position of the head of each pack unit has a predeterminedrelationship with the recording position determined by the correspondingtime management information, each pack unit can be recorded on themagnetic tape in anticipation of a margin in the reproduction.Accordingly, a space required for a buffer memory in the reproductionside can be decreased and the buffer memory can be appropriated forother processing, if required, thus efficiently structuring the entirevideo tape recorder.

The present invention is applied to a video tape recorder in which themanagement information serving as a reproduction reference, themanagement information being generated from time management informationwhen the video data is decompressed and output, is generated such thatthe management information serving as the reproduction reference isvaried in proportion to a clock serving as a processing reference whenthe video data is decompressed.

With the structure of the video tape recorder according to the presentinvention, the management information serving as a reproductionreference, the management information being generated from timemanagement information when the video data is decompressed and output,is generated such that the management information serving as thereproduction reference is varied in proportion to a clock serving as aprocessing reference when the video data is decompressed. Hence, asimple process can determine the relationship between the managementinformation serving as the reproduction reference and the process ofdecompressing the data. In addition, this determination result can beutilized in a variety of processing, thus efficiently structuring theentire video tape recorder.

The present invention is applied to a method of recording data on amagnetic tape. The recording method includes a pack-unit generating stepof blocking the video data in units of a predetermined number of blocksto generate a pack unit including a combination of the video data in theblock, the corresponding audio data, and the related data; amanagement-information generating step of generating managementinformation serving as a reproduction reference when the video data isreproduced from the magnetic tape, from time management information whenthe video data is decompressed and output; a delay step of delaying thepack-unit; a recording step of recording the pack unit on the magnetictape along with the management information serving as the reproductionreference; and a controlling step of varying a delay time generated inthe delay step. The controlling step varies the delay time such that therecording position of the head of each pack unit is set to a positionhaving a predetermined relationship with the recording positiondetermined by the management information serving as the correspondingreproduction reference.

The present invention is applied to a method of recording data on amagnetic tape. The recording method includes a pack-unit generating stepof blocking the video data in units of a predetermined number of blocksto generate a pack unit including a combination of the video data in theblock, the corresponding audio data, and the related data; amanagement-information generating step of generating managementinformation serving as a reproduction reference when the video data isreproduced from the magnetic tape, from time management information whenthe video data is decompressed and output; and a recording step ofrecording the data in the pack unit on the magnetic tape along with themanagement information serving as the reproduction reference. Themanagement-information generating step generates the managementinformation serving as the reproduction reference such that themanagement information serving as the reproduction reference is variedin proportion to a clock serving as a processing reference when thevideo data is decompressed.

With the structure described above according to the present invention,it is possible to provide a recording method capable of efficientlyrecording the data on the magnetic tape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a tape format in a video tape recorderaccording to an embodiment of the present invention.

FIG. 2 is a diagram showing an allocation of sectors in the tape formatin FIG. 1.

FIG. 3 is a diagram showing a pattern of a preamble.

FIG. 4 is a diagram showing the structure of a main sector.

FIG. 5 is a diagram showing a sink pattern.

FIG. 6 is a diagram showing an ID.

FIG. 7 includes diagrams showing a sink block header.

FIG. 8 is a diagram showing an average allocation of logical data in themain sector.

FIG. 9 includes diagrams showing the structure of a sink block whenauxiliary data is allocated to main data.

FIG. 10 is a diagram showing a fixed-length packet structure.

FIG. 11 is a diagram showing a variable-length packet structure.

FIG. 12 is a diagram showing keyword numbers.

FIG. 13 is a diagram showing the keyword numbers in the variable-lengthpacket structure.

FIG. 14 is a diagram showing an audio frame packet.

FIG. 15 is a diagram showing a video frame packet.

FIG. 16 is a diagram illustrating a search mode.

FIG. 17 is a diagram illustrating search data.

FIG. 18 is a diagram showing an ECCTB packet.

FIG. 19 is a diagram showing the structure of a sink block when thesearch data is allocated to the main data.

FIG. 20 is a diagram showing a packet header.

FIG. 21 is a diagram showing the structure of a sub-code sector.

FIG. 22 is a diagram showing the sink in the sub-code sector.

FIG. 23 is a diagram showing the ID in the sub-code sector.

FIG. 24 is a diagram showing the content of the sub-code data in thesub-code sector.

FIG. 25 is a diagram showing the structure of the sub-code data insub-code sink block numbers 0, 4, and 9.

FIG. 26 is a diagram showing the settings of flags.

FIG. 27 is a diagram showing the setting of the flag in a leastsignificant bit.

FIG. 28 is a diagram showing a sub-code to which an extended tracknumber is allocated.

FIG. 29 is a diagram showing a sub-code to which a title time code isallocated.

FIG. 30 is a diagram showing an allocation of the search data.

FIG. 31 is a diagram showing a recorded image of the main data.

FIG. 32 includes diagrams illustrating the process of the main data.

FIG. 33 includes diagrams showing the relationship with packing in apack unit.

FIG. 34 shows the relationship of a series of data relating to the packunit.

FIG. 35 includes diagrams illustrating the relationship between the maindata and the sub-code data.

FIG. 36 is a diagram illustrating the recording in the pack unit.

FIG. 37 is a block diagram showing the structure of a recording system.

FIG. 38 is a block diagram showing part of the structure in FIG. 37 indetail.

FIG. 39 is a block diagram showing the structure of a reproductionsystem.

FIG. 40 is a block diagram showing part of the structure in FIG. 39 indetail.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below withreference to the attached drawings.

(1) Structure of First Embodiment

(1-1) Recording Format

FIG. 1 is a plan view showing a recoding format when a video taperecorder according to an embodiment of the present invention recordsdata on a magnetic tape. The video tape recorder uses a magnetic-tapetraveling system approximately the same as in a video tape recorder in adigital video (DV) mode. Accordingly, pairs of diagonal tracks (trackpairs) having approximately the same pattern as that of a video taperecorder in the DV mode are continuously formed on the magnetic tape.One diagonal track in each pair has a positive azimuth angle and theother diagonal track therein has a negative azimuth angle. Referring toFIG. 1, HEAD denotes the scanning direction of a magnetic head and TAPETRAVEL denotes the traveling direction of the magnetic tape. Recordingtracks are sequentially produced at a speed of about 300 tracks/sec. Therecording rate on the magnetic tape is set to about 40 [Mbps].

A recording track having no pilot signal recorded therein, a recordingtrack having a pilot signal of a frequency F0 recorded therein, and arecording track having a pilot signal of a frequency F1 recorded thereinare sequentially and circularly formed on the magnetic tape. In thisstructure, the magnetic tape is subjected to tracking control based onthe pilot signals. The recording frequency of channel bits of datarecorded on each of the recording tracks is set so as to be 1/90 and1/60 with respect to the frequencies F0 and F1, respectively.

In a sequence of tracks formed in the manner described above in thevideo tape recorder of this embodiment, 16 tracks are set to aninterleave processing unit or an error correction process unit (ECCblock). The data recorded on the 16 tracks is sequentially compiled intoone block and an interleave process or an error correction process isperformed in each block. Track pair numbers from 0 to 31 aresequentially and circularly allocated to the track pairs of therecording tracks. The track pair number of the first track pair forinterleave is set to 0, 7, 15, or 23.

FIG. 2 is a diagram showing a sector format in each of the recordingtracks formed in the manner described above. A preamble, a main sector,a sub-code sector, a postamble, and an overwrite margin are continuouslyformed on the recording track from the side of the magnetic head wherethe scanning is started. On the recording track, a range where themagnetic tape is wound around a rotating drum at an angle of 174°measured from the side where the scanning is started is allocated tothese preamble, main sector, sub-code sector, and postamble. When videodata having a field frequency of 59.94 [Hz] is recorded (when therotating drum mounted on the magnetic head rotates at a rotational speedof 60×1000/1001 [Hz]), data of 134975 bits, represented by the amount ofdata after 24-to-25 modulation described below, is recorded in thisrange. When video data having a field frequency of 50 [Hz] is recorded(when the rotating drum rotates at a rotational speed of 60 [Hz]), dataof 134850 bits is recorded in this range.

In the preamble, data of 1800 bits, required for locking a PLL circuitduring reproduction, is recorded. FIG. 3 is a diagram showing recordingpatterns in the preamble. According to this embodiment, a combination ofa pattern A and a pattern B formed by inverting the bits of the patternA is allocated to each recording track to form a combination of thepilot signals described above.

In the main sector, video data or the like used in ordinary reproductionor in search is recorded in units of sink blocks described below. Atotal of 130425 bits is ensured for the main sector. In the sub-codesector, sub-codes are recorded. The sub-codes are data provided for, forexample, searching positions in a high-speed search. An areacorresponding to 1250 bits is ensured for the sub-code sector. For thepostamble, an area corresponding to 1500 bits is ensured when therotating drum rotates at a rotational speed of 60×1000/1001 [Hz] (whenthe field frequency is 59.94 [Hz]), and an area corresponding to 1375bits is ensured when the rotating drum rotates at a rotational speed of60 [Hz] (when the field frequency is 50 [Hz]). The postamble isstructured in the same manner as in the preamble.

The overwrite margin is provided for ensuring a margin duringoverwriting. An area corresponding to 1250 bits is ensured for theoverwrite margin.

FIG. 4 is a diagram showing the basic structure of the main sector. Theamount of data before the 24-to-25 modulation is shown in FIG. 4. Themain sector has 141 sink blocks each having 888 bits (111 bytes). A16-bit sink and a 24-bit ID are allocated to the head of each sinkblock, and a CI code, which is an inner code of an error correcting codein a product code mode, is allocated to trail 80 bits. In 123 sinkblocks, among 141 sink blocks, in the main sector, an 8-bit header (sinkblock header) and main data of 760 bits are allocated to the remaining768 bits. In contrast, in the remaining 18 sink blocks, a C2 code, whichis an outer code of the error correcting code in the product code mode,is allocated to the remaining 768 bits.

The sink is provided for detecting the position of each sink block. Apattern M0 and a pattern M1 formed by inverting the bits of the patternM0, shown in FIG. 5, are alternately allocated to the sink.

The ID is provided for, for example, identifying the sink block, asauxiliary data for the error correction. The ID has three kinds of ID0to ID2 shown in FIG. 6. Specifically, in the ID, first eight bits from 0to 7 are set to the first ID0. The five bits from 0 to 4 in the firstID0 represent the track pair numbers.

In the first three bits from 5 to 7 in the first ID0 in the ID, theformat of the track, described above with reference to FIG. 2, isrecorded. That is, identification information concerning the track isallocated to the first ID0.

In contrast, sink block numbers for identifying the sink blocks areallocated to the second ID1.

Information for determining whether the main sector is newly created orremains as a result of deletion of previous data relating to overwritingduring editing or the like, is allocated to the third ID2 as overwriteprotect data. Accordingly, in this video tape recorder, when previousdata cannot be completely deleted due to head clock or the like duringoverwriting, erasure correction is performed by using only the C2 codein order not to erroneously reproduce the previous data.

FIG. 7 includes diagrams showing the sink block header. In the sinkblock header, bits from b7 to b5 represent a data type indicating thekind of the main data, and bits from b4 to b0 represent detailedinformation of each data type. Specifically, when null data having nomeaning is allocated to the main data to form an empty sink block, thebits from b7 to b5 are set to a value of zero and the bits from b4 to b0are reserved.

When auxiliary data (AUX) of the video data and audio data is allocatedto the main data, the bits from b7 to b5 are set to a value of one. Inthis case, a mode (AUX mode) of this auxiliary data is allocated to thebits from b4 to b2. When the auxiliary data is auxiliary data relatingto packetized elementary stream (PES) video data (AUX-V), the bits fromb4 to b2 are set to a value of zero. When the auxiliary data isauxiliary data relating to PES audio data (AUX-A), the bits from b4 tob2 are set to a value of one. The PES video data and the PES audio dataare video data and audio data that are mainly recorded and reproduced bythe video tape recorder of this embodiment and that conform to anMPEG2-PES format.

When the auxiliary data is a first half of a program specificinformation (PSI) packet conforming to the MPEG2-PES format (PES-PSI1),the bits from b4 to b2 are set to a value of two. When the auxiliarydata is a last half of the PSI packet (PES-PSI2), the bits from b4 to b2are set to a value of three. When the auxiliary data is data of an ECCTBpacket described below, the bits from b4 to b2 are set to a value offour. When large meta data is allocated to the auxiliary data (AUX-M),the bits from b4 to b2 are set to a value of five. Values of six andseven in the bits from b4 to b2 are reserved. System data, here, is datarelating to a control sequence. The system data includes textinformation concerning copyright, a situation in the capture of images,or the like, which has been externally input as additional video oraudio data; a title time code (TTC), which is auxiliary data for search,editing, or the like; track position information; installing informationof the device; and so on.

Corresponding to these values, a flag DF indicating an invalid recordingarea in the recording in the ECCTB is allocated to the bit b1 or a flagFRC indicating a reversed polarity in a boundary between frames in themain data is allocated to the bit b1. A flag SBSC indicating an on stateof scramble control in the sink block header is allocated to the bit b0.The bit b1 is allocated to the flag FRC when the bits from b4 to b2 areset to a value of zero or five, is allocated to the flag DF when thebits from b4 to b2 are set to a value of four, and is reserved when thebits from b4 to b2 are set to values other than zero, five, and four.

In contrast, when the main data is video data conforming to theMPEG2-PES format (PES-VIDEO), the bits from b7 to b5 are set to a valueof two. When the main data is audio data conforming to the MPEG2-PESformat (PES-AUDIO), the bits from b7 to b5 are set to a value of three.In these two cases, the bit b4 indicates whether the data is partial (95bytes or less) or full (95 bytes). A continuity counter value isallocated to the bits from b3 to b0.

In contrast, when the main data is a first half of data recorded in atransport stream format (TS-1H), the bits from b7 to b5 are set to avalue of four, a jump flag is allocated to the bits b4 and b3, and atime stamp is allocated to the bits from b2 to b0. When the main data isa last half of the data recorded in the transport stream format (TS-2H),the bits from b7 to b5 are set to a value of five, and a continuitycounter value is set to the bits from b4 to b0.

When the main data is search data (SEARCH), the bits from b7 to b5 areset to a value of six and the bit b4 is reserved. In this case, thecorresponding search speed is recorded in the bits from b3 to b1, andthe flag SBSC indicating an on state of the scramble control isallocated to the bit b0. The search data is data of low-frequencycomponents of an I picture. When the bits from b3 to b1 are set to avalue of two or four, the search data is set so as to instruct an 8× or24× search speed, respectively. The value 7 in the bits from b3 to b1 isreserved.

FIG. 8 is a diagram showing an average allocation of logical data in thedata structure of the main sector formed in the manner described above.A C2 code is allocated to eighteen sink blocks such that errorcorrection can be continuously performed for two tracks or more (=12.5%(=two tracks/16-track ECC (error correcting code) interleave)) to setthe continuous error correction rate to 12.7 [%]. The auxiliary data(AUX)+the NULL data is set to 95 bytes×2.2 SB×300 tracks×8 bits=501[Kbps], the video data is set to 95 bytes×110 SB×300 track×8 bits=25.021[Mbps], the audio data is set to 95 bytes×1.8 SB×300 tracks×8 bits=421[Kbps], and the search data is set to 95 bytes×9.1 SB×300 tracks×8bits=2.07 [Mbps]. These figures add up to a total of 28.044 [Mbps] (95bytes×123 SB×300 tracks×8 bits). Hereinafter, the sink block isappropriately denoted by SB.

As described above, the video data, the audio data, and thecorresponding system data (auxiliary data) are sequentially allocatedand recorded as the main data in the main sector on the magnetic tape.

FIG. 9 includes diagrams showing the structure of the sink block whenthe auxiliary data is allocated to the main data. When a mode (AUX mode)of the auxiliary data is a value of zero (the auxiliary data isauxiliary data concerning the video data (AUX-V)), is a value of one(the auxiliary data is auxiliary data concerning the PES audio data(AUX-A), or is a value of five (large metadata is allocated (AUX-M)), afirst byte in a main data area subsequent to the sink header isallocated to a sub-header in each sink block (FIGS. 9(A) and 9(B)).

In the sub-header, bits from b7 to b4 are reserved and bits from b3 tob0 are allocated to a continuity counter value. The sub-header isprovided for detecting the continuity of data based on the continuitycounter value when the auxiliary data is allocated across multiple sinkblocks. Accordingly, this continuity counter value can be reproducedwithout fail by setting an independent continuity counter value forevery mode of the auxiliary data even when a plurality of pieces of theauxiliary data is irregularly allocated. Incidentally, the sub-header isnot provided in the ECCTB packet because the auxiliary data, which isthe system data and is recorded in the ECCTB packet, is regularlyallocated and the auxiliary data has continuity. The ECCTB packet is asink block allocated for recording the head of the ECC block, which willbe described in detail below.

The auxiliary data in the data allocated to the main sector is allocatedto the main data described above with reference to FIG. 4. The auxiliarydata has packet structures shown in FIGS. 10 and 11.

FIG. 10 is a diagram showing a packet structure of fixed-lengthauxiliary data and FIG. 11 is a diagram showing a packet structure ofvariable-length auxiliary data. The packet structure of the fixed-lengthauxiliary data is mainly allocated to the sub-code sector while alsobeing allocated to the main sector. The entire packet structure of thefixed-length auxiliary data has five bytes. Bits b7 and b6 in a firstbyte are set to a value of zero, a keyword number indicating the contentof each auxiliary data is allocated to bits from b5 to b0, and theremaining four bytes are allocated to the auxiliary data.

In contrast, in the packet structure of the variable-length auxiliarydata, bits b7 and b6 in a first byte are set to values of zero and one,respectively, and a keyword number indicating the content of eachauxiliary data is allocated to bits from b5 to b0. A number n of bytesof subsequent auxiliary data is recorded in the subsequent one byte todetect the length of the packet. The auxiliary data is allocated to theremaining n bytes.

FIG. 12 is a diagram showing the keyword numbers in the packet structureof the fixed-length auxiliary data. A series of numbers are allocated tothe keyword number in the packet structure of the fixed-length auxiliarydata and the packet structure of the variable-length auxiliary data.Values from 0 to 63 are allocated to the packet structure of thefixed-length auxiliary data. The values from 0 to 7, among the 63values, are applied to the sub-code sector. A value of zero indicatesthat the subsequent four bytes denote a title time code (TTC). A valueof one in the keyword number indicates that the subsequent four bytesare data in a binary group, and a value of two in the keyword numberindicates that the subsequent four bytes denote a part number.

A value of four in the keyword number indicates that the subsequent fourbytes denote tape position information (ATNF) and a predetermined flag(FLG). The tape position information is 23-bit absolute-positioninformation and is represented by a track number (ATN: absolute tracknumber) counted from the head of the tape to each recording track. Theflag (FLG) is set to a value of one when the tape position informationis not continuous. It is possible to perform the search without fail bydetermining the continuity of a sequence of tracks based on the value ofthe flag (FLG). A value of five indicates that the subsequent four bytesdenote a recording date and a value of six indicates that the subsequentfour bytes denote a recording time. A value of seven indicates that thesubsequent four bytes denote an extended track number (ETN).

The extended track number ETN is management information serving as areproduction reference when the video data is reproduced from themagnetic tape. A value representing time management information DTS(decoding time stamp) by using the track number according to thefollowing relational expression is applied to the extended track numberETN so as to be in proportion to the time management information DTS(decoding time stamp) of the video data in the decoding and so as to bein proportion to a system time clock STC that is an operation referencein the decoding and that is an operation reference of the video taperecorder. The extended track number ETN is represented by 24 bits. Thecontent of bits from b4 to b0 denotes the track number in the ECC andthe content of bits from b5 to b1 coincides with the track pair number.The track number in the ECC is a number when the first track of the ECCis set to a value of zero. The time management information DTS in thedecoding is a count value at a frequency of 90 [kHz] and is an outputreference of the decoded and decompressed video data.

With respect to the title time code TTC, when the recording format isapplied to a system having a field frequency of 59.94 [Hz], the TTC isrepeatedly allocated in a cycle of 10 tracks and the ETN is representedby an integral multiple of 10 at the beginning of the TTC. When therecording format is applied to a system having a field frequency of 50[Hz], the TTC is repeatedly allocated in a cycle of 12 tracks and theETN is represented by an integral multiple of 12 at the beginning of theTTC.

Accordingly, according to this embodiment, when the recording format isapplied to a system having a field frequency of 59.94 [Hz], the extendedtrack number is represented by DTS=EFN×3003=ETN×3003/10. When therecording format is applied to a system having a field frequency of 50[Hz], the extended track number is represented byDTS=EFN×3600=ETN×3600/12. The EFN denotes an extended frame number,which is a frame number corresponding to the extended track number ETN.In the first ID0, values from 8 to 62 are reserved and a value of 63indicates that the subsequent four bytes are null.

FIG. 13 is a diagram showing the keyword numbers in the packet structureof the variable-length auxiliary data. Values from 64 to 127 areallocated to the packet structure of the variable-length auxiliary data.Among these keyword numbers, values from 64 to 67 are allocated to theauxiliary data of the audio data. The value 64 indicates that theauxiliary data of the audio data is allocated to the subsequent variabledata. The remaining values from 65 to 67 are reserved.

Values from 68 to 79 are allocated to the auxiliary data of the videodata. The value 68 indicates that the auxiliary data of the video datais allocated to the subsequent variable data. The value 73 indicatesthat the subsequent variable data is data compatible with the DV mode.The values of 77 and 78 indicate that the subsequent variable data isdata of a message in an ASCII code and a message in a shift JIS code,respectively. The value 79 indicates that the subsequent variable datais binary data.

Values from 80 to 83 are allocated to the system. The value 80 indicatesthat the subsequent variable data forms an ECCTB packet. Values from 84to 119 are reserved. Values from 120 to 126 indicate that the subsequentvariable data is large metadata. A value of 127 indicates that thesubsequent variable data is null to form a null packet.

FIG. 14 is a diagram showing an audio frame packet when the keywordnumber is set to a value of 64, among these settings of the keywordnumber. As described above in the packet structure in FIG. 11, in theaudio frame packet, a first byte is set to the keyword number having avalue of 64 and a number n of subsequent bytes (=92) is allocated to thesubsequent one byte. An operation mode for outputting a transport streamis set to the subsequent one byte. A VTR mode, tape position information(ATNF) and various flags (EFL and FLG), and a title time code, whichhave the same content as those of the corresponding video frame, areallocated to the subsequent five, three, and five bytes, respectively.In this manner, a pack pair of the corresponding video data can easilybe identified in a pack unit. The pack unit means a combination of thecorresponding video data, audio data, and system data. These variousflags (EFL and FLG) will be described in detail in a description of apacket corresponding to the sub-codes described below.

Information concerning an original recording date and time is allocatedto the subsequent 10 bytes, information concerning a recording date andtime on the magnetic tape is allocated to the subsequent eight bytes,and information indicating a copy generation is allocated to thesubsequent one byte. Status information concerning an editing point(editing information) is allocated to the subsequent two bytes for everybyte, and an audio mode is allocated to the subsequent six bytes. Theaudio mode here includes a frame size, a sampling frequency, and so on.The subsequent four bytes are reserved, and information concerning thepack unit is allocated to the subsequent 11 bytes. The informationconcerning the pack unit, here, is reference information for decodingand includes frame numbers, the number of frames, and a presentationtime stamp (PTS).

FIG. 15 is a diagram showing a video frame packet when the keywordnumber is set to a value of 68, among these settings of the keywordnumber. As described above in the packet structure in FIG. 11, in thevideo frame packet, a first byte is set to the keyword number having avalue of 68 and a number n of subsequent bytes (=92) is allocated to thesubsequent one byte. An operation mode for outputting a transport streamis set to the subsequent one byte. A VTR mode, tape position information(ATNF) and various flags (EFL and FLG), and a title time code, whichhave the same content as those of the corresponding audio frame, areallocated to the subsequent five, three, and five bytes, respectively.

A binary time code is allocated to the subsequent five bytes.Information concerning an original recording date and time is allocatedto the subsequent 10 bytes, information concerning a recording date andtime on the magnetic tape is allocated to the subsequent eight bytes,and information indicating a copy generation is allocated to thesubsequent one byte. In the video frame packet, sub-code data to whichthe time management information DTS is allocated is allocated withoutchange to the fourth to 39-th bytes. When the corresponding video datais a B picture or a C picture, the data is associated with thecorresponding I picture or P picture.

Status information concerning an editing point (editing information) isallocated to the subsequent two bytes for every byte, and a recordingmode of search data is allocated to the subsequent one byte. The searchdata is allocated in association with each search speed, as shown inFIG. 16. Information concerning the pack unit is allocated to thesubsequent 11 bytes. The content of an MPEG video stream header isallocated to the information concerning the pack unit here. In the dataconcerning the pack unit, information indicating an I picture, a Ppicture, and the like and information indicating the end of recording(V-END) are allocated to information DATA-H concerning pictures, asshown in FIG. 17.

Information concerning a video mode is allocated to the subsequent 16bytes. Additional information for every frame (extended DV pack) isallocated to the subsequent one byte and subsequent 15 bytes.

FIG. 18 is a diagram showing an ECCTB packet when the keyword number isset to a value of 80. Information recorded on 16 tracks, which form aninterleave unit, is allocated to the ECCTB packet that is recorded inthe head and a fixed position of the interleave unit, as describedabove. As described above in the packet structure in FIG. 11, in theECCTB packet, a first byte is set to the keyword number having a valueof 80 and a number n of subsequent bytes (=93) is allocated to thesubsequent one byte. Information having the same content as in thesub-code in the first track of interleave is recorded in the subsequent37 bytes. The information includes tape position information ATNF andvarious flags (EFL and FLG), an ETN, a title time code TTC, a binarygroup, information concerning an original recording date and time,information concerning a recording date and time on the magnetic tape,and a copy generation.

Editing information concerning the video is allocated to the subsequent25 bytes. After a status concerning an editing point, a search datamode, and so on are allocated, information concerning the video data andthe audio data (video mode and audio mode) is allocated.

FIG. 19 is a diagram showing the structure of a sink block in the searchdata. In the sink block, the header of a search sink block is allocatedto first 40 bits and the search data is allocated to the remaining 720bits. In the header here, an X address and a Y address in the coordinatesystem of a head macroblock, which are recorded in the sink block, areallocated with a reserved one bit sandwiched therebetween. A packet ID(PC ID), a packet header, and packet data are subsequently allocated.

The packet header is set so as to indicate the content of the packetdata. As shown in FIG. 20, values from two to seven indicate a varietyof displayed information similar to that described above with respect tothe keyword number and values from 8 to 11 indicate positionalinformation for a search.

FIG. 21 is a diagram showing the structure of the sub-code sector. Thesub-code sector is used for high-speed search at, for example, a speedof about two hundred times. After the 24-to-25 modulation, the entiresub-code sector has 1250 bits that are divided into 10 sub-code sinkblocks. In each of the sub-code sink blocks, first 16 bits are allocatedto a sink and the subsequent 24 bits are allocated to an ID. Thesubsequent 40 bits are allocated to sub-code data and the remaining 40bits are allocated to parity bits.

A predetermined pattern S0 and a pattern S1 formed by inverting the bitsof the pattern S0, which are different from the patterns M0 and M1 inthe sink in the main sector, are allocated to the sink, as shown in FIG.22. The main sector can be discriminated from the sub-code sector basedon the patterns M0 and M1 and the patterns S0 and S1.

The ID in the sub-code sector includes a first ID0, a second ID1, and athird ID2, as shown in FIG. 23. The first ID0 defines format types (FTYPE) and track pair numbers, as in the sink ID in the main sector.Sub-code sink block numbers (SB numbers) in the sub-code sector areallocated to the second ID1 and part of the second ID1 is reserved.Overwrite protect data is allocated to the third ID2, as in the sink IDin the main sector. When it is determined that the data recorded in thesub-code sector remains as a result of deletion of previous data, thecorresponding sink block is processed as an invalid sink block becauseof the setting of the overwrite protect data.

FIG. 24 is a diagram showing the content of the sub-code data in thesub-code sector. Information shown in FIG. 24 is recorded in thesub-code sector in accordance with the packet structure described abovewith reference to FIG. 10. As for the sub-code data, the same data isrecorded in the tracks in an even-numbered track pair and the same datais recorded in the tracks in an odd-numbered track pair in accordancewith the fixed-length data format described above with reference to FIG.10. However, the sub-code data has a structure different from the packetstructure described above with reference to FIG. 10 in the sub-code sinkblock numbers 0, 4, and 9. Various flags and tape position information(ATNF) are allocated to the sub-codes having the sub-code sink blocknumbers 0, 4, and 9 in the even-numbered track pair and the odd-numberedtrack pair.

FIG. 25 is a diagram showing the structure of the sub-code data in thesub-code sink block numbers 0, 4, and 9. In this sub-code data, variousflags are recorded in a first byte. FIG. 26 is a diagram showing thesettings of the flags. The presence of search data and a phasedifference between the sub-code data and the main data are recorded.

In contrast, a blank flag BF indicating track numbers (ATN) with respectto the head of the tape are discontinuous is set in a bit b0 in thesecond byte. The blank flag BF is set to the same value in the recordingsince the track numbers have once become discontinuous. A track number(ATN) with respect to the head of the tape is allocated to the thirdbyte. The track number (ATN) is the same as in the DV mode. A first bitin the track number (ATN) is allocated to a code.

Various flags shown in FIG. 27 are set in a last byte. The flags hereinclude an I flag indicating a search point, a P flag that is set whenstill pictures start to be recorded at a position in the main data, a PFflag indicating that an I picture or a P picture is allocated to themain data, and an EF flag relating to editing.

In contrast, extended track numbers ETN are allocated to the sub-codeshaving the sub-code sink block numbers 1 an 6 in the even-numbered trackpair and to the sub-code having the sub-code sink block number 5 in theodd-numbered track pair (FIG. 24).

FIG. 28 is a diagram showing a sub-code to which an extended tracknumber ETN is allocated. In the sub-code, the corresponding keywordnumber is allocated to bits from b5 to b0 in a first byte and anextended track number ETN is allocated to the third byte.

In contrast, title time codes TTC are allocated to the sub-codes havingthe sub-code sink block numbers 2, 5, and 7 in the even-numbered trackpair and to the sub-codes having the sub-code sink block number 1 and 6in the odd-numbered track pair (FIG. 24).

FIG. 29 is a diagram showing a sub-code to which a title time code isallocated. In the sub-code, a keyword number is allocated to bits fromb5 to b0 in a first byte and information concerning the time code issequentially allocated to the subsequent bytes.

In contrast, no information is allocated to the sub-codes having thesub-code sink block numbers 3 and 8 in the even-numbered track pair(FIG. 24). Information concerning recording date and time is allocatedto the sub-codes having the sub-code sink block number 2 and 7 in theodd-numbered track pair. Information concerning recording time isallocated to the sub-codes having the sub-code sink block number 3 and 8in the odd-numbered track pair.

FIG. 30 is a diagram showing an allocation of the search data recordedin the main sector and the sub-code sector on the magnetic tape.Recording positions of the search data are defined based on physicalpositions after interleave. The search data for 8×speed is allocated ata rate of one per one ECC bank (16 tracks).

Specifically, in the search data for 8×speed, two pieces of the samedata corresponding to 17 sink blocks (data numbers from 17 to 33) arerepeatedly recorded in the recording tracks having the track numbersETN[3:0]=0 and 4 in the ECC. Three pieces of data corresponding to theremaining 17 sink blocks (data numbers from 0 to 16) are repeatedlyrecorded in the recording track having the track number ETN[3:0]=2 inthe ECC. Accordingly, 34 sink blocks (data numbers from 0 to 33) areallocated to one ECC bank.

In contrast, one piece of the search data for 24× speed is allocated forevery three ECC banks (16×3=48 tracks). The recording positions areindicated by a two-bit ternary counter in a search phase (SPH) in asub-code flag extension (FLE). In the search data for 24×speed, fourpieces of the data corresponding to eight sink blocks (data numbers from0 to 3 and from 8 to 11) are repeatedly recorded in the recording trackshaving the track numbers ETN[3:0]=11 and 15 in the ECC. Three pieces ofdata corresponding to the four sink blocks (data numbers from 4 to 7)are repeatedly recorded in the recording track having the track numberETN[3:0]=13 in the ECC. Accordingly, the data corresponding to 12 sinkblocks is repeatedly recorded in three ECC blocks.

The search data is searched and used based on, for example, TTCs fordisplay in the sub-codes, described above with reference to FIG. 20.

FIG. 31 is a diagram showing a recorded image of the main data recordedin the main sector and the sub-code sector on the magnetic tape. In thisembodiment, the video data and audio data compressed in an MPEG formatincluding MP@HL and MP@H-14 are recorded. The video data is dividedbased on I pictures and P pictures in a GOP relating to data compressionto be blocked, and the video data in each block, the corresponding audiodata, and the corresponding auxiliary data are combined to form a packunit. In the example shown in FIG. 31, reference letters I, P and Bdenote an I picture, a P picture, and a B picture, respectively.Subsequent to a first I picture, pictures B, B, P, B, B, P . . . aresequentially allocated, and the ratio of I, B, B, P pictures isrepresented by 4:1:1:2. Referring to FIG. 31, for every ECC unit, whichis an interleave unit, top and bottom figures denote ECC block numbersand alphanumeric characters inside the ECC block numbers denote tracknumbers in the ECC unit.

At a first track in a first sink block for every ECC unit on themagnetic tape, the auxiliary data is recorded in ECC packets (shown byreference letter H). In each pack unit, the audio data (shown byreference letter A) is recorded after the auxiliary data concerning theaudio data (shown by reference letter X) is recorded, and the auxiliarydata concerning the video data (shown by reference letter U) is thenrecorded. Subsequently, each picture is recorded in the order ofstreaming. When the audio data is 384 [Kbps], the audio data isallocated in 50 sink blocks on the average.

The pack units are continuously recorded with the sink block having theNULL data and the main data sandwiched therebetween, as required, inorder to ensure an appropriate delay time. Accordingly, in thisembodiment, the head of each of the pack units is recorded at apredetermined position determined based on the time managementinformation DTS in the decoding.

Specifically, in this embodiment, the NULL data is recorded in the headof each of the pack units such that the corresponding time managementinformation DTS on the magnetic tape is preceded by a number greaterthan the number of tracks given by adding a preceding amount αcorresponding to a predetermined number of tracks to a video bufferingverifier (vbv) delay in the decoding. The end position of each of thepack units is set so as to surely precede the corresponding timemanagement information DTS on the magnetic tape. The preceding amount αis 16 tracks here.

As shown in FIG. 32, in this embodiment, the video data input in abaseband (FIG. 32(B)) is compressed in the MPEG format (FIG. 32(C)) toproduce a video ENC delay caused by encoding the video data. A case inwhich continuous pictures are encoded into B, B, I, B, B, and P picturesis shown in FIG. 32(B). In contrast, the corresponding audio data A1 toA4 (FIG. 32(F)) is compressed (FIG. 32(E)) to produce an audio ENC delaycaused by encoding the audio data. The audio data A1 to A4 hererepresents each frame having a length of 24 [msec], which is a datacompression unit of the audio data. Reference letters AXA and AXV denotethe auxiliary data of the audio data and the auxiliary data of the videodata, respectively.

The compressed video data and audio data form a pack unit along with thecorresponding auxiliary data. The pack unit is subjected totime-division multiplexing (FIG. 32(D)) and is recorded on the magnetictape (FIG. 32(A)). In the recording on the magnetic tape, in the audiodata Al to A4, the delay time in the trail audio data A4, which forms apack unit along with the I pictures, is a minimum delay time on themagnetic tape, whereas the delay time in the audio data A1 allocated atthe head of the pack unit subsequent to the pack unit including the Ipicture is a maximum delay time on the magnetic tape. It is understoodthat the video buffering verifier (vbv) delay in the decoding is varieddue to the amount of codes generated in the compression of the data, avariety of auxiliary data, insertion of the search data, or the like.

FIG. 33 includes diagrams showing the relationship with packing in eachpack unit. An example in which the recording is started from the first Ipicture in the video data input in the baseband is shown in FIG. 33 (A).In the baseband input, the I, B, and B pictures, the corresponding audiodata, and the corresponding auxiliary data form a pack unit P1. As theauxiliary data here, the auxiliary data AUX-A of the audio data, theauxiliary data AUX-V of the video data, and so on are provided. Inaddition, the title time code TTC and the like are generated and areallocated to the auxiliary data.

A pack unit EP1 including CO and C1, which is an editing pack unit at anediting point, is inserted for matching with the vbv delay required forediting. FIG. 34 shows the relationship of a series of data relating tothese pack units.

As shown by arrows (FIG. 33(A)), according to this embodiment, the datastream input in the baseband is multiplexed (FIG. 33(B)), the main datais recorded in each pack unit on the magnetic tape, and thecorresponding auxiliary data is recorded in the sub-codes on themagnetic tape (FIG. 33(C)). The stream of the main data is recorded at apreceding position with respect to the time management information DTSof the sub-code that is recorded at a position determined by thecorresponding time management information DTS. The search data isrecorded from an ECC bank subsequent to the corresponding I picture andthe corresponding time management information DTS. While the video datais reallocated by reordering during encoding, the audio data and theauxiliary data are recorded on the magnetic tape in the order of input.

The extended track number ETN of the head of the I picture is 120 inorder to provide a positive value at the head of the stream. The sameapplies to the track number (ATN). Incidentally, when the recording isstarted with the extended track number ETN and the track number (ATN)being set to a value of zero, the time management information DTS on themagnetic tape corresponding to a time given by adding the videobuffering verifier (vbv) delay in the decoding to a time periodcorresponding to an ECC block is 30 to 100 tracks. However, inself-encoding, in consideration of using a common extended track numberETN and a common track number (ATN) in a system having a field frequencyof 59.94 [Hz] and a system having a field frequency of 50 [Hz], a valueof 120 having the same least common multiple of the number of frames andtracks in these systems is set as first values of the extended tracknumber ETN and the track number (ATN).

According to this embodiment, the video data and the audio data isreproduced and decoded in this manner described above on the basis ofeach auxiliary data in the sub-code sector recoded on the magnetic tape(FIG. 33(D)). The search data (FIG. 33(E)) is generated with the Ipicture of the corresponding video data, and is recorded from an ECCbank subsequent to the corresponding I picture and the correspondingtime management information DTS, as described above.

On the magnetic tape, the main data has a relationship shown in FIG. 35with the sub-code data. FIG. 35 illustrates the relationship of therecording position between the sub-code and the head of thecorresponding pack unit with respect to the first frame of the packunit. For a system having a field frequency of 59.95 [Hz], the sub-codeis formed in units of 10 tracks in one frame. The same content isrepeatedly recorded in the sub-code data corresponding to 10 tracks inthe frame in the structure described above with reference to FIG. 24.

The main data is set so as to precede the extended track number ETN ofthe sub-code, which is the DTS on the magnetic tape, by a time given byadding a preceding amount corresponding to a predetermined number oftracks to the vbv delay in the decoding and such that the trail of thepack unit does not exceed the position determined by the time managementinformation DTS. However, a shift in the position where the recording ofthe pack unit is started is allowed, as shown in FIGS. 35(D) to 35(E).

A shift T1 at the starting position, which is varied due to insertion ofthe auxiliary data and the search data, can be estimated in a mannerdescribed below. In this case, delaying the entire reproduction processallows the data in each pack unit to be decoded after the timedetermined by the time management information DTS. However, this delayonly shifts the reference time backward and an additional delay isrequired for the data to be recorded in the sub-code, thus complicatingthe process.

Among elements that vary the shift T1 at the starting position, amaximum shift caused by the density of the search data is 1.6 tracksboth at 8× and 24× speeds, as described above. The amount of thecorresponding audio data is 0.7 tracks and that of the auxiliary data isthree tracks/three frames. The amount of the NULL data is 1.0 track whenthe position where the pack unit starts to be recorded is postponed inunits of tracks. A total of the amount of data is 6.3 tracks.

Hence, according to this embodiment, the preceding amount αcorresponding to a predetermined number of tracks should be set to 6.3or more, thereby permitting continuous reproduction in video and audiostreams. In consideration of further expandability, this precedingamount α is set to 16 tracks according to the format convention.

Specifically, when the preceding amount α is set to 9 to 12 tracks,which is larger than 6.3 tracks, an additional margin allows theauxiliary data (AUX-M) to be collectively recorded. In this case, it ispossible to intermittently record the data of around 100 [KB]corresponding to 10 tracks. It is also possible to record additionalsearch data for 4× speed, 16× speed, or the like, in addition to thesearch data for the 8× speed and the 24× speed. Recording suchadditional search data reduces the rate of the video data by an amountcorresponding to the additional search data. In a system using a commonmemory in the recording and reproduction, a margin corresponding to afew frames is left in the reproduction, thus utilizing this margin invarious processes. In other words, setting the maximum preceding amountin the recording to four tracks allows, in the reproduction side, thecompliance to the extended format described above, and allows the amountof memory corresponding to 16 tracks to be ensured. In this case, it ispossible to save the amount of memory by an amount corresponding to oneframe, compared with a case where an additional system is structured.

FIGS. 35(A), 35(B), and 35(C) show the main data, the sub-code data, andthe search data, respectively. FIG. 35(D) shows an example of recordingin a maximum preceding amount and FIG. 35(E) shows an example ofrecording after a maximum delay. Referring to FIGS. 35(A) to (E), a vbvdelay of one second corresponds to 300 tracks. Accordingly, in thisembodiment, a margin of a period T2 is left both between the trail ofthe pack unit and the corresponding DTS and between the trail of the Ipicture and the corresponding DTS.

In the process of setting the head of the pack unit, as shown by areference letter A in FIG. 36 in contradistinction to FIG. 31, when thevbv delay in the decoding is converted into 62.7 tracks, adding 16,which is the number of tracks for interleave, to 62 given by truncatingthe fractions after the decimal point of 62.7 produces 78 tracks.Accordingly, when the extended track number ETN, which is a position onthe magnetic tape determined by the time management information DTS, isa value of 80, the NULL data is allocated such that the correspondingpack unit is recorded from a position having a extended track number ETNof two, which precedes the position of the extended track number ETN by78 tracks. Referring to FIG. 36, 10 tracks correspond to the period ofone frame and the ECCTB packets are not shown here.

At the head of the pack unit shown by reference letter B, the vbv delayin the decoding is converted into 50.4 tracks. In this case, the numberof tracks calculated in the same manner described above is 66. Thenumber of tracks shifts by 30 tracks, compared with the case shown bythe reference letter A, and the ETN is 110. The NULL data is allocatedsuch that the corresponding pack unit is recorded from a position atwhich ETN=44. The value 44 is given by subtracting the value 66 fromETN=110.

At the head of the pack unit shown by reference letter C, the vbv delayin the decoding is converted into 57 tracks. In this case, the number oftracks calculated in the same manner described above is 73. Since theETN has a value of 140, subtracting a value of 73 from 140 gives theETN=67. In this case, the ETN has a value of 68 even without insertionof the NULL data. Since the position has already exceeded the startingposition of recording, the pack unit is recorded without allocating theNULL data.

The reason why the continuous pack units are delayed from the startingposition of recording having the maximum preceding amount and there isno need to insert the NULL data is that the amount of codes generated bydata compression is small in the three pictures constituting the packunit. The same situations occur when multiple factors, including a casewhere the amount of the AUX data is large in the pack units, a casewhere a delay (a maximum of one track) occurs due to insertion of theNULL data, and a case where the search data is recorded during the delaytime, are simultaneously caused.

(1-2) Video Tape Recorder

FIG. 37 is a block diagram showing the recording system in a video taperecorder according to an embodiment of the present invention. FIG. 38 isa block diagram showing part of the recoding system in detail. In avideo tape recorder 1, video data and audio data are compressed in theformat, described above with reference to FIGS. 1 to 36, in the MPEG,MP@HL, MP@14, or another format and recorded on a magnetic tape 2 and/orthe compressed and recorded video data and audio data are reproduced anddecoded.

Specifically, in the video tape recorder 1, a video-data compressingunit 3 compresses video data HDV sequentially input in a formatconforming to MPEG2 (MP@HL or HM@14) under the rate control by acontrolling unit 8 and outputs the compressed data along with a varietyof time information and so on. Specifically, the video-data compressingunit 3 includes a video encoder 3A, a DTS/PTS generator (DTS/PTS GEN)3B, an ETN generator (ETN GEN) 3C, and a video FIFO 3D (FIG. 38). Thevideo encoder 3A compresses the video data HDV and outputs the videodata as a PES signal having a header, a time stamp, and the like addedthereto. The DTS/PTS generator 3B detects time information from thevideo data HDV and outputs time management information DTS and a PTSbased on this time information. The ETN generator 3C calculates andoutputs an extended track number ETN based on the result output from theDTS/PTS generator 3B according to the relational expression describedabove. The video FIFO 3D temporarily stores the video data output fromthe video encoder 3A and outputs the stored video data. According tothis embodiment, 15 pictures form one GOP and one P picture is set forevery three pictures subsequent to a first I picture in the GOP. Bpictures are set in the remaining pictures in the GOP.

A search-data generating unit 4 generates search data and outputs thegenerated search data by selecting an I picture from the video data andselecting data of a low-frequency component from the encoded data of theI picture.

An audio-data compressing unit 5 receives audio data DA corresponding tothe video data HDV, compresses the audio data DA in a format conformingto MPEG Layer2, and outputs the compressed audio data at a rate from 256to 384 [Kbps]. Specifically, in the audio-data compressing unit 5, anaudio encoder 5A compresses the audio data DA and outputs the compressedaudio data, and an audio FIFO 5B temporarily stores the data output fromthe audio encoder 5A and outputs the stored audio data.

An auxiliary-data generating unit 6 generates auxiliary data and outputsthe generated auxiliary data. Specifically, the auxiliary-datagenerating unit 6 includes a sub-code generator 6A, an auxiliary-datagenerator for video 6B, and an auxiliary-data generator for audio 6C.The sub-code generator 6A generates the corresponding auxiliary databased on a variety information input along with the video data HDV andthe audio data DA and outputs the generated auxiliary data. Theauxiliary-data generator for video 6B generates auxiliary data of thecompressed video data output from the video encoder 3A and outputs thegenerated auxiliary data. The auxiliary-data generator for audio 6Cgenerates auxiliary data of the compressed audio data output from theaudio encoder 5A and outputs the generated auxiliary data. An ECCTBgenerator (ECCTB GEN) 6D generates auxiliary data required for an ECCTBpacket and outputs the generated auxiliary data.

A multiplexing unit 7 multiplexes the compressed video data, audio data,search data, and auxiliary data along with NULL data and outputs themultiplexed data. Specifically, in the multiplexing unit 7, a NULLgenerator (NULL GEN) 7A generates, for example, NULL data in which allthe bits are set to a predetermined logical value and outputs thegenerated NULL data, and a multiplexer (MUX) 7B sequentially multiplexesthe NULL data, the video data and audio data output from the FIFOs SBand 6B, and the search data and auxiliary data output from thesearch-data generating unit 4 and the auxiliary-data generator 6C underthe control of a controller 7C and outputs the multiplexed data.Accordingly, the video tape recorder 1 is structured so as to generate adata stream constituting a sink block.

In the processing described above, the controller 7C calculates theamount of the auxiliary data, search data, and the like for every packunit, and controls the operation of the multiplexer 7B such that theNULL data is inserted in accordance with the vbv delay in the decodingdescribed above. An ECC memory 7D temporarily stores the data outputfrom the multiplexer 7B for every ECC block and outputs the stored datain a predetermined order to perform interleave process. In thisprocessing, the data output from the ECCTB generator 6D, the data outputfrom the ETN generator 3C, and the like are inserted and output attimings at which the ECCTB packet and the sub-code sector are allocated.

A sub-code generating unit 10 generates a sub-code data stream in thesub-code sector and outputs the generated data stream. An error-code-IDadding unit 9 adds an error correcting code, an ID, and so on to thedata output from the multiplexing unit 7 and the data output from thesub-code generating unit 10 to produce data streams in the main sectorand the sub-code sector. Specifically, the sub-code generating unit 10includes the ETN generator 3C, the sub-code generator 6A, and so ondescribed above. In the error-code-ID adding unit 9, an ID and ECC adder9A adds the ID and the error correcting code to the data output from theECC memory 7D and outputs the added data. An ID and ECC adder 9B addsthe ID and the error correcting code to the data output from thesub-code generator 6A and outputs the added data. An adder 9C collectsthe data output from the ID and ECC adders 9A and 9B into one line andoutputs the collected data to a 24-to-25 modulating unit 11.

The 24-to-25 modulating unit 11 performs 24-to-25 modulation for thedata output from the error-correcting-code ID adding unit 9 and outputsthe modulated data. A sink adding unit 12 adds a sink to the data outputfrom the 24-to-25 modulating unit 11 and outputs the added data. Amodulating unit and P/S converting unit 13 performs NRZI (non return tozero inverted) modulation for the data output from the sink adding unit12 to convert the modulated data into a serial data stream and drivesthe magnetic head 14 mounted on a rotating drum based on the serial datastream. The controlling unit 8 is a controller for controlling theoperation of each circuit block. The video tape recorder 1 having thestructure described above sequentially records the video data, the audiodata, and so on on the magnetic tape 2 in the format described above.

In the structure described above according to this embodiment, themultiplexer 7B serves as pack-unit generating means for blocking thevideo data in units of predetermined blocks to generate a pack unitincluding a combination of the video data in the blocks, thecorresponding audio data, the relating auxiliary data, and the searchdata. The ETN generator 3C serves as management-information generatingmeans for generating management information ETN, serving as areproduction reference when the video data is reproduced from themagnetic tape, from time management information DTS when the video datais decompressed and output. The multiplexer 7B and the NULL generator 7Aserve as delay means for delaying the data output from the pack-unitgenerating means by inserting sink blocks including NULL data betweenthe multiplexer 7B and NULL generator 7A and the respective precedingadjacent pack units to delay the pack unit. The circuit blocksdownstream of the multiplexer 7B serve as a recording system forrecording the data output from the pack-unit generating means on themagnetic tape along with the management information ETN. The controller7C serves as controlling means for varying a delay time generated in thedelay means.

According to this embodiment, the delay time generated in the delaymeans is varied such that a first recording position of each pack unitis set to a position having a predetermined relationship with therecording position determined by the management information ETN servingas the corresponding reproduction reference, based on the settings ofthe amount of delay in the delay means. The head of each pack unit,which is the position having the predetermined relationship, precedesthe recording position determined by the management information ETNserving as the reproduction reference corresponding to the timemanagement information DTS in a decoder for decompressing the video dataand outputting the decompressed data by an amount given by adding apredetermined preceding amount α to the vbv delay in the decoding at thehead of the pack unit. The preceding amount α is at least a valuecorresponding to an average amount of data other than the video data inthe pack unit.

FIG. 39 is a block diagram showing the reproduction system of the videotape recorder 1. FIG. 40 is a block diagram showing part of thereproduction system in detail. In this reproduction system, a digitalconverting unit and S/P converting unit 21 amplifies a signal outputfrom the magnetic head 14 by an amplifier (not shown) and then performsan analog-to-digital conversion process, for example, performs Viterbidecoding, to reproduce the data input in the modulating unit and P/Sconverting unit 13 in the recording system. The digital converting unitand S/P converting unit 21 converts the data reproduced into paralleldata and outputs the parallel data.

A demodulating unit 22 performs a process corresponding to the NRZImodulation during the recording to demodulate the data output from thedigital converting unit and S/P converting unit 21 and outputs thedemodulated data. A sink detecting unit 23 detects a sink in each sinkblock based on the data output from the demodulating unit 22 andnotifies an error-correcting ID detecting unit 24 and so on of a timingof the detection of the sink. A 25-to-24 converting unit 25 reproducesthe data input in the 24-to-25 modulating unit 11 in the recordingsystem by performing 25-to-24 conversion for the data output from thedigital converting unit and S/P converting unit 21 and outputs the datareproduced.

The error-correcting ID detecting unit 24 pastes the SB number and thetrack number, detected from the ID, of the data subsequent to the ID inthe data output from the 24-to-25 modulating unit 11 in an ECC bank 24Abased on the timing of the detection of the sink notified by the sinkdetecting unit 23, performs the error correction process and theinterleave process in an error corrector 24B, and outputs the processeddata. Specifically, the ECC bank 24A has three banks including a bankfor writing the input data, a bank for performing the ECC process in theerror corrector 24B, and a bank for outputting the data to a separatingcircuit 27.

A sub-code detecting unit 26 detects a sub-code sink block from thesub-code sink, performs the error correction, and outputs the processeddata. Specifically, in the sub-code detecting unit 26, a sub-code ECC26A acquires the sub-code data by selectively acquiring the data of thesub-code sector from the data output from the 24-to-25 modulating unit11 and performing the error correction process and outputs the acquireddata, and a sub-code FIFO 26B outputs the sub-code data to a centralprocessing unit (CPU) 8A, which corresponds to the controlling unit 8.

The separating circuit 27 separates the data output from theerror-correcting ID detecting unit 24 into processing units based on theSB header and outputs the separated data. In the separating circuit 27,a SB detector 27A detects each SB header to detect the main data in eachsink block, and a demultiplexer 27B outputs the data output from theerror-correcting ID detecting unit 24 to the processing units based onthe detection result in the SB detector 27A.

A video-data decompressing unit 28 receives the video data from theseparating circuit 27, and decompresses and outputs the video data, incontrast to the time of the recording. In the video-data decompressingunit 28, a video FIFO 28A temporarily stores the data output from theseparating circuit 27 and outputs the stored data, and a video decoder28B decompresses the data output from the video FIFO 28A and outputs thedecompressed data. The video tape recorder 1 can output the video dataHDV, which is a result of the reproduction, in this manner describedabove.

According to this embodiment, the video FIFO 28A for temporarily storingand outputting the video data is set so as to be have a capacity greaterthan the capacity corresponding to a preceding amount by which a firstrecording position of each pack unit precedes the recording positionwhere the management information serving as the correspondingreproduction reference is recorded in the recording system.

A search-data detecting unit 29 receives search data from the separatingcircuit 27, generates video data from the search data, and outputs thegenerated video data. In the search-data detecting unit 29, a searchdecoder 29A receives the search data from the separating circuit 27,interpolates a part that was not able to be captured, and generates andoutputs the video data, and a search auxiliary-data detector 29Bacquires auxiliary data added to the search data and notifies thecentral processing unit (CPU) 8A of the auxiliary data.

An audio-data decompressing unit 30 receives the audio data from theseparating circuit 27, and decompresses and outputs the audio data. Inthe audio-data decompressing unit 30, an audio FIFO 30A temporarilystores the audio data output from the separating circuit 27 and outputsthe stored audio data, and an audio decoder 30B decompresses the audiodata and outputs the decompressed audio data. With this structure, thevideo tape recorder 1 can output the audio data DA, which a result ofthe reproduction.

An auxiliary-data detecting unit 31 detects auxiliary data from theseparating circuit 27 and outputs the detected auxiliary data to thecontrolling unit 8. In the auxiliary-data detecting unit 31, anauxiliary-data FIFO 31A temporarily stores the auxiliary data outputfrom the separating circuit 27 and outputs the auxiliary data to thecontrolling unit 8, and an auxiliary-data generator FIFO 31B temporarilystores the auxiliary data output from the separating circuit 27,converts the auxiliary data into a format corresponding to outputsincluding the video data, the audio data, and the like, and outputs theconverted auxiliary data to the central processing unit 8A.

In this manner, the controlling unit 8 controls these circuit blocks inthe reproduction system, as in the recording system. In other words, thecentral processing unit BA in the controlling unit 8 performs aprocedure recorded in a memory (not shown) to control all the circuitblocks. In this processing, a system-time-clock STC generator 8Bgenerates a system time clock STC, which is an operation reference ofthe video tape recorder 1, and outputs the system time clock STC. Areference ETN generator 8C generates an ETN that is a comparisonreference from the system time clock STC and outputs the ETN. Atape-drum servo circuit 8D rotates and drives a capstan motor 8F and adrum motor 8E to drive the magnetic tape 2 at a predetermined speed, androtates and drives the rotating drum wound around the magnetic tape 2 ata predetermined speed. In this processing, the tape-drum servo circuitBD compares the comparison reference ETN generated by the reference ETNgenerator 8C with the ETN determined by the reproduction result obtainedfrom the data output from the demodulating unit 22 (ETN supplied fromthe sub-code detecting unit 26) to control the rotational phase of thecapstan motor 8F such that the comparison reference ETN coincides withthe ETN determined by the reproduction result. Accordingly, the videotape recorder 1 can scan the magnetic tape 2 with the magnetic head 14by the same track trace as in the recording.

According to this embodiment, the processing circuit from the magnetichead 14 to the error-correcting-code ID detecting unit 24 serves aspack-unit reproduction means for processing a reproduction signalsupplied from the magnetic tape 2 to reproduce the data in the packunit. The demultiplexer 27B serves as data separating means forseparating the video data from the data in the pack unit supplied fromthe pack-unit reproduction means. The video FIFO 28A serves as storingmeans for temporarily storing the video data output from the dataseparating means and outputting the stored video data. The video decoder28B serves as data decompressing means for decompressing the data outputfrom the storing means and outputting the decompressed data.

In the recording and reproduction systems represented as the blocks inthe video tape recorder 1, the FIFOs 3D, 5B, 6B, and 6C in the recordingsystem are structured so as to be used commonly with the FIFOs 28A, 30A,31A, and 31B in the reproduction system. These FIFOs in the recordingsystem are provided for achieving the timing shown in FIG. 32. Althoughnot shown in figures, the reproduction system achieves a reverse timing,compared with the timing in FIG. 32, to realize the same relationshipbetween the video data and the audio data output from the reproductionsystem as between the video data and the audio data input in therecording system.

(2) Operation of Embodiment

In the video tape recorder 1 having the structure described above (FIGS.37 and 38), during the recording, the video data HDV and the audio dataDA are compressed in the MPEG format in the video encoder 3A in thevideo-data compressing unit 3 and the audio encoder 5A in the audio-datacompressing unit 5 to generate the video data and the audio data in thePES transport stream. The search generator 4 serving as the search-datagenerating unit 4 selects data corresponding to low-frequency componentsfrom the data in the I picture in the compressed video data to generatesearch data for 8× speed and 24× speed. The auxiliary data forgenerating the sub-code is generated by the auxiliary-data generatingunit 6 by using the information concerning each picture in the videodata, the auxiliary data input along with the video data, and so on.

In the generation of the auxiliary data in the video tape recorder 1,the DTS/PTS generator 3B generates the time management information DTSat a frequency of 90 [kHz], which serves as a reference when the videodata HDV is output. The extended track number ETN is generated based onthe time management information DTS according to an equationETN=DTS/300.3 when the video data HDV has a field frequency of 59.94[Hz] or according to an equation ETN=DTS/360 when the video data HDV hasa field frequency of 50 [Hz]. The extended track number ETN is timeinformation serving as a reproduction reference when the compressedvideo data recorded on the magnetic tape 2 is reproduced.

In the video tape recorder 1, the compressed video data and audio data,the auxiliary data, and the search data are subjected to multiplexing inthe multiplexer 7B, are stored in the ECC memory 7D, and are output fromthe ECC memory 7D in a predetermined order, thereby allocating the datato the main sector as the main data and to the sub-code sector to besubjected to interleave. Subsequently, the ID and the error correctingcodes C1 and C2 are added to the data output from the ECC memory 7D.After the added data is subjected to the 24-to-25 modulation in the24-to-25 modulating unit 11, a sink is added to the modulated data inthe sink adding unit 12. Accordingly, the video data, the audio data,part of the auxiliary data, and the search data are converted into thedata stream (FIG. 4) in the main sector structure. In contrast, theauxiliary data is converted into the data stream (FIG. 21) in thesub-code sector structure similar to that in the main sector structure.After the data stream in the main sector structure and the data streamin the sub-code sector structure are subjected to the NRZI modulation inthe converting unit 13, the modulated data is converted into the serialdata stream and the converted data is recorded on the magnetic tape 2.At this time, in the video tape recorder 1, the postamble, the preamble,and so on are added to these data streams. The added data issequentially and diagonally recorded on the magnetic tape 2 in theformat shown in FIG. 2. In this processing, the ECC memory 7D iscontrolled such that the error correction process and the interleaveprocess are performed for every 16 tracks on the magnetic tape 2, andthe error correcting code is generated. Hence, in the video taperecorder 1, the DTS, the STP, the ETN, and so on are allocated to thesub-code, and the corresponding video data and audio data are recordedon the magnetic tape 2.

In the video tape recorder 1, the video data recorded on the magnetictape 2 in the manner described above is compressed into a GOP including15 pictures. Then, the video data forming one GOP including 15 picturesis divided in units of three pictures to generate pack data of the videodata. In the video tape recorder 1, the pack data of the video data, thecorresponding audio data, and the auxiliary data forms a pack unit. Thevideo data, the audio data, and the auxiliary data are recorded on themagnetic tape 2 in units of the pack unit (FIG. 31). In each pack unit,the auxiliary data concerning the audio data, the audio data, and theauxiliary data concerning the video data are compiled at the side of thehead to be sequentially recorded on the magnetic tape 2. Accordingly,the video data and so on recorded on the magnetic tape 2 in units of thepack unit can be processed in the video tape recorder 1.

In the video tape recorder 1, in addition to the recording in units ofthe pack unit, the ECCTB packet of the auxiliary data is allocated tothe first sink block of the first track in each interleave unit in orderto improve the performance of the processing, such as continuousrecording. In addition, the search data for 8× speed and 24× speed isrecorded at a predetermined position, thus achieving a high-speedsearch.

Each time the video data, the audio data, and the auxiliary data arerecorded in units of sink blocks in the video tape recorder 1, the vbvdelay in the decoding is determined for every pack unit in thecontroller 7. A position that precedes the vbv delay by a time periodcorresponding to a predetermined preceding amount that is greater than atime required for recording an average amount of data other than thevideo data in the pack unit on the magnetic tape is set to the recordingposition of the pack unit. Accordingly, the processing in the ECC memory7D is controlled by the controller 7C such that the first recordingposition of the pack unit has a predetermined relationship with therecording position where the time information ETN serving as thereproduction reference is recorded and which corresponds to the head ofthe pack unit.

As described above, since the memories 3D and 28A are used in common inthe recording system and the reproduction system in the video taperecorder 1, a margin is left in the space in these memories duringreproduction, thus ensuring a high expandability.

In other words, when the head of each pack unit is not specified, it isnecessary to provide a memory in the reproduction side to delay the packunit. Accordingly, a large memory must be provided in the reproductionsystem. However, according to this embodiment, each pack unit can berecorded on the magnetic tape in anticipation of a margin in thereproduction and, therefore, the space of the buffer memory required forthe reproduction side can be decreased. In a system in which therecording system shares the memory with the reproduction system, thebuffer memory required in the recording system can be appropriated forthe reproduction side. Actually, when the preceding amount correspondingto six tracks, which is a shift occurring in the recording of theauxiliary data or the like, is anticipated in the recording system, itis possible to accommodate a time shift more than the amountcorresponding to 16 tracks described above in the format in thereproduction side.

From a reverse point of view, anticipating such a margin allows a largemargin for recording a variety of data other than the video data and theaudio data to be provided. For example, it is possible to record theauxiliary data of around 5 to 10 tracks (50 to 100 [KB]) for every twoto five seconds. Furthermore, search data having a higher-definition canbe recorded and search data having a search speed other than the searchspeed described above can be recorded. Anticipating a shift in therecording position in the reproduction side by 16 tracks decreases thevideo rate to 2 [Mbps] and increases the auxiliary data corresponding tothe decrease in the video rate. Even when the video tape recorder 1 isapplied to a system in which LPCM data of 2 [Mbps] is recorded, it ispossible to accurately record and reproduce the video data.

Anticipating such a preceding amount allows the relationship with thesub-code and the relationship with the search data to be definitized. Inother words, preceding the head of the pack unit in the manner describedabove allows detection of the corresponding sub-code, and the recordingposition of a desired main stream can be determined based on thesub-code. In addition, it is sufficient to provide a narrow range inwhich the main data is searched from the sub-code. Accordingly, it ispossible to reproduce a desired main data in a short period of time.Furthermore, it is possible to easily determine a first packet evenwhen, for example, packets are subjected to continuous recording.

Specifically, when the video data and the like recorded on the magnetictape 2 is reproduced in the video tape recorder 1 in the mannerdescribed above (FIGS. 39 and 40), the reproduction signals suppliedfrom the magnetic head 14 are sequentially processed, the sub-codes aredetected by the sub-code detecting unit 26, and the controlling unit 8is notified of the auxiliary data in the sub-codes. The reproductionposition, the auxiliary data of the video data recorded on the magnetictape, and the like are detected by the controlling unit 8. The videodata, the audio data, and the like that are separated by the separatingcircuit 27 and are then decompressed are output.

For example, when a user instructs to perform a search process in theprocessing described above, the reference ETN generator 8C in the videotape recorder 1 generates the extended track number ETN, serving as acomparison reference, based on the system time clock STC generated inthe system-time-clock STC generator 8B. The phase of the extended tracknumber ETN serving as the comparison reference is compared with that ofthe extended track number ETN provided from the magnetic tape 2 toperform phase control for the capstan motor BF. The magnetic tape 2 isdriven at a high speed to selectively scan the track having the searchdata recorded therein with the magnetic head 14, and the search data isseparated from the data in the main sector provided as a result of thescanning by the separating circuit 27. The search data is processed bythe search-data detecting unit 29 to output the video data for a search.

In contrast, in the ordinary reproduction, the extended track numbersETN generated based on the system time clock STC are sequentiallyconverted in accordance with the time management information DTS in thedecoder in the ordinary reproduction. The video data and the audio datarecorded on the magnetic tape 2 are sequentially decompressed andoutput. In this processing, in the video tape recorder 1, the extendedtrack number ETN is set so as to be in proportion to the time managementinformation DTS in the video data in the decoding and so as to be inproportion to the system time clock STC serving as an operationreference in the decoding. Hence, the operation of the servo system canbe controlled based on the extended track number ETN to constitute theservo system and the stream processing system by using one reference,thus simplifying the entire structure of the video tape recorder 1.

Setting the extended track number ETN in this manner allows the extendedtrack number ETN to be recorded in the header of the main data todetermine whether the extended track number ETN is correctly recorded bycomparing the sub-code and the stream header. Based on the comparisonresult, it is possible to effectively avoid, for example, reproducingincorrect data. In other words, confirming a time in the time managementinformation DTS and the extended track number ETN having a predeterminedrelationship with this time management information DTS allows therecording position of the video data and the like on the magnetic tapeto be physically validated. In addition, the recording position and thephase of the search data for 8× speed can easily be detected from theextended track number ETN of the sub-code and a picture type owing tothe relationship with the ECCTB packet. In the video tape recorder 1,the corresponding search data precedes the maximum vbv delay representedby the extended track number ETN by 104 tracks.

(3) Advantages of Embodiments

With the structure described above, setting the recording position ofthe head of each pack unit to a position having a predeterminedrelationship with the recording position determined by the correspondingtime management information allows the entire video tape recorder to beefficiently structured.

The head of each pack unit, which is the position having thepredetermined relationship, precedes the recording position determinedby the management information serving as a reproduction referencecorresponding to the time management information in the decoder fordecompressing and outputting the video data by an amount given by addinga predetermined preceding amount to the delay time in the decoding atthe head of the pack unit, so that a desired recording position caneasily be detected.

When the predetermined preceding amount has a value corresponding to, atleast, an added time given by adding the time required for recording anaverage amount of data, other than the video data, in the pack unit onthe magnetic tape and when a delay memory in the recording system isshared with the reproduction process, the preceding amount capable ofbeing reproduced is increased and, therefore, the recorded data having awider range (preceding 16 tracks in this embodiment) can be reproduced.

Specifically, it is possible to appropriate a required memory for thereproduction side by inserting the NULL data such that the maximumpreceding amount in the recording is five tracks.

In other words, when the reproduction system shares a memory with therecording processing, a memory having a space more than the spacecorresponding to the preceding amount can be ensured, thus structuringthe entire video tape recorder without practically increasing therequired memory space.

Setting the trail of the pack unit so as to precede the recordingposition determined by the management information serving as thecorresponding reproduction reference can maintain the relationshipdescribed above with the head of each pack unit in the recording ofcontinuous pack units.

Generating the management information serving as a reproductionreference such that the management information serving as thereproduction reference varies in proportion to a clock serving as aprocessing reference when the video data is decompressed permitsrecording and reproduction of the video data with a simple structure andprocess, thus efficiently structuring the entire video tape recorder.

(4) Second Embodiment

According to a second embodiment, when the NULL data is allocated underthe condition with respect to the head and trail of the pack unitaccording to the first embodiment described above, the NULL data isinserted toward the trail of the track such that the head of thesubsequent pack unit reaches the head of the recording track. A videotape recorder according to the second embodiment is structured in thesame manner as in the video tape recorder of the first embodiment exceptthe NULL data that is additionally allocated.

Inserting the NULL data such that the head of the corresponding packunit reaches the head of the recording track, as described above, canfurther simplify the entire structure.

The insertion of the NULL data allows the head of the pack unit to bedetected in units of tracks to achieve a simple detection. In contrast,with the structure according to the first embodiment, it is necessary todetect the head of the pack unit in units of sink blocks. In the processof adding the tracks corresponding to the preceding amount (16 tracks)to the number of tracks corresponding to the vbv delay, it is sufficientto provide a simple 8-bit calculator capable of representing 104 tracksby using the number of preceding recorded tracks 10 in units of tracks,whereas it is necessary to perform a calculation process until a valueof 140 corresponding to the number of sink blocks is given in units ofsink blocks and, thus, requiring a 16-bit calculator having additionaleight bits. Accordingly, a simpler structure can be realized in thesecond embodiment.

If the NULL data is detected in the middle of a track when the NULL datais recorded in the manner described above, the subsequent search can befinished for this track, thus simplifying a variety of processing. Inaddition, it is also possible to improve error resilience by utilizingthe NULL data allocated in the manner described above in the errorcorrection.

(5) Other Embodiments

Although a case in which the data in the main stream is delayed byrecording the NULL data is described in the above embodiments, thepresent invention is not limited to this case and can be widely appliedto various delaying methods. For example, the present invention can beapplied to a case in which the data in the main stream is delayed byrepeatedly recording the same main data.

Although a case in which the video data compressed in the MPEG format isrecorded is described in the above embodiments, the present invention isnot limited to this case. The present invention can be widely applied tocases in which the video data compressed in various formats is recorded.

As described above, according to the present invention, setting therecording position of the head of each pack unit so as to have apredetermined relationship with the recording position determined by thecorresponding time management information allows the entire video taperecorder to be efficiently structured.

INDUSTRIAL APPLICABILITY

The present invention relates to a video tape recorder and a method ofrecording data on a magnetic tape. Particularly, the present inventioncan be applied to a video tape recorder that records a video signal ofthe HDTV on a magnetic tape.

1. A video tape recorder for sequentially and diagonally formingrecording tracks on a magnetic tape and recording compressed video data,compressed audio data, and data relating to the video data and the audiodata on the magnetic tape, the video tape recorder is characterized bycomprising: pack-unit generating means for blocking the video data inunits of a predetermined number of blocks to generate a pack unitincluding a combination of the video data in the block, thecorresponding audio data, and the related data; management-informationgenerating means for generating management information serving as areproduction reference when the video data is reproduced from themagnetic tape, from time management information when the video data isdecompressed and output; delay means for delaying data output from thepack-unit generating means; a recording system for recording the dataoutput from the pack-unit generating means on the magnetic tape alongwith the management information serving as the reproduction reference;and controlling means for varying a delay time generated in the delaymeans, wherein the controlling means varies the delay time generated inthe delay means such that the recording position of the head of eachpack unit is set to a position having a predetermined relationship withthe recording position determined by the management information servingas the corresponding reproduction reference and wherein the head of eachpack unit, which is the position having the predetermined relationship,precedes the recording position determined by the management informationserving as the reproduction reference corresponding to the timemanagement information by an amount given by adding a predeterminedpreceding amount to the delay time in the decoding at the head of thepack unit.
 2. The video tape recorder according to claim 1,characterized in that the predetermined preceding amount has, at least,a value corresponding to an average amount of data, other than the videodata, in the pack unit.
 3. The video tape recorder according to claim 1,characterized in that the recording system inserts NULL data of, atleast, an amount corresponding to the delay time generated in the delaymeans into the data output from the pack-unit generating means.
 4. Thevideo tape recorder according to claim 3, characterized in that thecontrolling means sets the head of the corresponding pack unit to thehead of the recording track by inserting the NULL data.
 5. The videotape recorder according to claim 1, characterized in that thecontrolling means sets the trail of the pack unit to a positionpreceding the recording position determined by the managementinformation serving as the corresponding reproduction reference.
 6. Thevideo tape recorder according to claim 1, characterized by furthercomprising: pack-unit reproduction means for processing a reproductionsignal supplied from the magnetic tape to reproduce the data in the packunit; data separating means for separating the video data from the datain the pack unit reproduced by the pack-unit reproduction means; storingmeans for temporarily storing the video data output from the dataseparating means and outputting the stored video data; and datadecompressing means for decompressing the data output from the storingmeans and outputting the decompressed data, wherein the storing meanshas a capacity more than the amount corresponding to the precedingamount.
 7. A video tape recorder for sequentially and diagonally formingrecording tracks on a magnetic tape and recording compressed video data,compressed audio data, and data relating to the video data and the audiodata on the magnetic tape, the video tape recorder is characterized bycomprising: pack-unit generating means for blocking the video data inunits of a predetermined number of blocks to generate a pack unitincluding a combination of the video data in the block, thecorresponding audio data, and the related data; management-informationgenerating means for generating management information serving as areproduction reference when the video data is reproduced from themagnetic tape, from time management information when the video data isdecompressed and output; and a recording system for recording the datain the pack unit on the magnetic tape along with the managementinformation serving as the reproduction reference, wherein themanagement-information generating means generates the managementinformation serving as the reproduction reference such that themanagement information serving as the reproduction reference is variedin proportion to a clock serving as a processing reference when thevideo data is decompressed and wherein the recording position of eachpack unit precedes the reproduction reference generated by the timemanagement information by an amount given by adding a predeterminedpreceding amount to the processing reference.
 8. A recording method ofsequentially and diagonally forming recording tracks on a magnetic tapeand recording compressed video data, compressed audio data, and datarelating to the video data and the audio data on the magnetic tape, therecording method is characterized by comprising: a pack-unit generatingstep of blocking the video data in units of a predetermined number ofblocks to generate a pack unit including a combination of the video datain the block, the corresponding audio data, and the related data; amanagement-information generating step of generating managementinformation serving as a reproduction reference when the video data isreproduced from the magnetic tape, from time management information whenthe video data is decompressed and output; a delay step of delaying thepack-unit; a recording step of recording the pack unit on the magnetictape along with the management information serving as the a reproductionreference; and a controlling step of varying a delay time generated inthe delay step, wherein the controlling step varies the delay time suchthat the recording position of the head of each pack unit is set to aposition having a predetermined relationship with the recording positiondetermined by the management information serving as the correspondingreproduction reference and wherein the head of each pack unit, which isthe position having the predetermined relationship, precedes therecording position determined by the management information serving asthe reproduction reference corresponding to the time managementinformation by an amount given by adding a predetermined precedingamount to the delay time in the decoding at the head of the pack unit.9. A recording method of sequentially and diagonally forming recordingtracks on a magnetic tape and recording compressed video data,compressed audio data, and data relating to the video data and the audiodata on the magnetic tape, the recording method is characterized bycomprising: a pack-unit generating step of blocking the video data inunits of a predetermined number of blocks to generate a pack unitincluding a combination of the video data in the block, thecorresponding audio data, and the related data; a management-informationgenerating step of generating management information serving as areproduction reference when the video data is reproduced from themagnetic tape, from time management information when the video data isdecompressed and output; and a recording step of recording the data inthe pack unit on the magnetic tape along with the management informationserving as the reproduction reference, wherein themanagement-information generating step generates the managementinformation serving as the reproduction reference such that themanagement information serving as the reproduction reference is variedin proportion to a clock serving as a processing reference when thevideo data is decompressed and wherein the recording position of eachpack unit precedes the reproduction reference generated by the timemanagement information by an amount given by adding a predeterminedpreceding amount to the processing reference.